Unicode subscripts and superscripts

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Unicode has subscripted and superscripted versions of a number of characters including a full set of Arabic numerals. [1] These characters allow any polynomial, chemical and certain other equations to be represented in plain text without using any form of markup like HTML or TeX.

Contents

The World Wide Web Consortium and the Unicode Consortium have made recommendations on the choice between using markup and using superscript and subscript characters:

When used in mathematical context (MathML) it is recommended to consistently use style markup for superscripts and subscripts […] However, when super and sub-scripts are to reflect semantic distinctions, it is easier to work with these meanings encoded in text rather than markup, for example, in phonetic or phonemic transcription. [2]

Uses

The difference between superscript/subscript and numerator/denominator glyphs. In many popular computer fonts the Unicode "superscript" and "subscript" characters are actually numerator and denominator glyphs. Sub super num dem.svg
The difference between superscript/subscript and numerator/denominator glyphs. In many popular computer fonts the Unicode "superscript" and "subscript" characters are actually numerator and denominator glyphs.

The intended use [2] when these characters were added to Unicode was to produce true superscripts and subscripts so that chemical and algebraic formulas could be written without markup. Thus "H₂O" (using a subscript 2 character) is supposed to be identical to "H2O" (with subscript markup).

In reality, many fonts that include these characters ignore the Unicode definition, and instead design the digits for mathematical numerator and denominator glyphs, [3] [4] which are aligned with the cap line and the baseline, respectively. When used with the solidus or the Fraction Slash, they produce an almost typographically correct diagonal fraction, such as ³/₄ for the ¾ glyph. Super and subscript markup does not produce a correct fraction (compare markup 3/4 with precomposed ¾). The change also makes the superscript letters useful for ordinal indicators, more closely matching the ª and º characters.

Unicode intended that diagonal fractions be rendered by a different mechanism: the fraction slash U+2044 is visually similar to the solidus, but when used with the ordinary digits (not the superscripts and subscripts), it instructs the layout system that a fraction such as ¾ is to be rendered using automatic glyph substitution. [5] [a] User-end support was quite poor for a number of years, but fonts, [b] browsers, [c] word processors, [d] desktop publishing software [e] and others increasingly support the intended Unicode behavior. This browser and your default font render it as 34. (See Slash (punctuation)#Fractions for rendering in various other fonts.)

Superscripts and subscripts block

The most common superscript digits (1, 2, and 3) were included in ISO-8859-1 and were therefore carried over into those code points in the Latin-1 range of Unicode. The remainder were placed along with basic arithmetical symbols, and later some Latin subscripts, in a dedicated block at U+2070 to U+209F. The table below shows these characters together. Each superscript or subscript character is preceded by a baseline x to show the height of subscripting/superscripting.

Unicode characters
0123456789ABCDEF
U+00Bx
U+207x x⁰xⁱx⁴x⁵x⁶x⁷x⁸x⁹x⁺x⁻x⁼x⁽x⁾xⁿ
U+208x x₀x₁x₂x₃x₄x₅x₆x₇x₈x₉x₊x₋x₌x₍x₎
U+209x xₐxₑxₒxₓxₔ xₕxₖxₗxₘ xₙxₚxₛxₜ xxx
  Reserved for future use.
  Other characters from Latin-1 not related to super- or sub-scripts.

Other superscript and subscript characters

Unicode also includes codepoints for subscript and superscript characters that are intended for semantic usage, in the following blocks: [1] [6]

Superscript
Combining superscript
Subscript
Combining subscript

Latin, Greek, Cyrillic, and IPA tables

A superscript small-cap W may be distinct from a superscript lowercase w in italic typeface, as in this phonetic notation. Superscript small cap W.png
A superscript small-cap W may be distinct from a superscript lowercase w in italic typeface, as in this phonetic notation.

Consolidated, the Unicode standard contains superscript and subscript versions of a subset of Latin, Greek and Cyrillic letters. Here they are arranged in alphabetical order for comparison (or for copy and paste convenience). Since these characters appear in different Unicode ranges, they may not appear to be the same size or position due to font substitution by the browser. Shaded cells mark petite capitals that are not very distinct from minuscules in roman typeface, but they may be distinct in italic typeface, as is used in some phonetic notation.

Little punctuation is encoded. Parentheses are shown in the basic superscript block above, and the exclamation mark is shown in the IPA table below. In a supporting font, a question mark may be created with a superscript gelded question mark and a combining dot below: ˀ̣.

Latin superscript and subscript letters
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Superscript capitalᴿ*
Superscript petite cap*𐞄**𐞒𐞖*𐞪𐞲
Superscript minusculeʰʲˡ𐞥ʳˢʷˣʸ
Overscript small cap◌ᷛ◌ᷞ◌ᷟ◌ᷡ◌ᷢ
Overscript minuscule◌ͣ◌ᷨ◌ͨ◌ͩ◌ͤ◌ᷫ◌ᷚ◌ͪ◌ͥ◌ᷜ◌ᷝ◌ͫ◌ᷠ◌ͦ◌ᷮ◌ͬ◌ᷤ◌ͭ◌ͧ◌ͮ◌ᷱ◌ͯ◌ᷦ
Subscript minuscule***
Underscript minuscule◌᷊◌ᪿ

*Superscript versions of S, of petite capital A, D, E and P, of ƀ, and subscript versions of w, y and z have been accepted for a future version of the Unicode Standard. [8] [9] [10] [11]

Additional Latin characters
ÆɃƎŊ
Superscript capital
Superscript minuscule𐞃*
Overscript minuscule◌ᷔ◌ᷪ
Subscript minuscule

Some of these superscript capitals are small caps in the source documents in the Unicode proposals.

Shaded cells Greek letters that are indistinguishable from Latin, and so would not be expected to be supported by Unicode.

Greek superscript and subscript letters
ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩ
Superscript minuscule [A] ᶿ [A] **
Overscript minuscule [A] ◌ᷩ
Subscript minusculeͺ [f]
Underscript minuscule◌ͅ◌̫ [g]
  1. 1 2 3 In some fonts, Latin alpha ᵅ and upsilon ᶹ can be used as superscript Greek alpha and upsilon. ᵋ and ᶥ are also officially Latin letters, but display the same as Greek.

*Superscript versions of Greek psi and omega have been accepted for a future version of the Unicode Standard. [10] [9]

Russian superscript and subscript letters
А Б В Г Д Е Ж З И К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
Superscript𞀰𞀱𞀲𞀳𞀴𞀵𞀶𞀷𞀸𞀹𞀺𞀻𞀼𞀽𞀾𞀿𞁀𞁁𞁂𞁃𞁄𞁅𞁆𞁇𞁈𞁉
Overscript◌ⷶ◌ⷠ◌ⷡ◌ⷢ◌ⷣ◌ⷷ◌ⷤ◌ⷥ◌ꙵ◌ⷦ◌ⷧ◌ⷨ◌ⷩ◌ⷪ◌ⷫ◌ⷬ◌ⷭ◌ⷮ◌ꙷ◌ꚞ◌ⷯ◌ⷰ◌ⷱ◌ⷲ◌ⷳ◌ꙸ◌ꙹ◌ꙺ◌ⷻ
Subscript𞁑𞁒𞁓𞁔𞁕𞁖𞁗𞁘𞁙𞁚𞁛𞁜𞁝𞁞𞁟𞁠𞁡𞁢𞁣𞁤𞁥𞁦
Additional modern Cyrillic characters
Ә Ґ Є Ѕ І Ї Ј Ө Ҫ Ү Ұ Џ Ӏ
Superscript𞁋𞁊𞁌𞁌̈𞁍𞁎𞁫𞁏𞁭𞁬𞁐
Overscript◌ꙴ𞂏◌ꙶ
Subscript𞁧𞁩𞁨𞁨̈𞁪
Additional medieval Cyrillic characters
Ѡ Ѣ Ѥ Ѧ Ѫ Ѭ Ѳ
Overscript◌ⷹ◌ꙻ◌ⷺ◌ⷼ◌ꚟ◌ⷽ◌ⷾ◌ⷿ◌ⷴ

Superscript and subscript ё, ї, й, ў etc. are handled with diacritics, 𞀵̈ 𞁌̈ 𞀸̆ 𞁁̆etc. Many of the Cyrillic characters were added to the Cyrillic Extended-D block, which was added to the free Gentium Plus and Andika fonts with version 6.2 in February 2023.

See also small caps in Unicode.

Superscript IPA

The Latin Extended-F block was created for the remaining superscript IPA letters. They are supported by the free Gentium Plus and Andika fonts. Additional superscript characters for historical and para-IPA letters have been accepted for future versions of the Unicode Standard. [11] [9]

Consonant letters

The Unicode characters for superscript (modifier) IPA and extIPA consonant letters are as follows. The entire Latin Extended-F block is dedicated to superscript IPA. Characters for sounds with secondary articulation are set off in parentheses and placed below the base letters.

IPA and extIPA consonants, along with superscript variants and their Unicode code points
Bi­labialLabio­dentalDentalAlveolarPost­alveolarRetro­flexPalatalVelarUvularPharyn­gealGlottal
Nasalm 
1D50
ɱ 
1DAC
n 
207F
()
 
 
(ȵ)
ɳ 
1DAF
ɲ 
1DAE
ŋ 
1D51
ɴ 
1DB0
Plosivep 
1D56
b 
1D47
t 
1D57
(ƫ )
1DB5
d 
1D48
()
 
 
(ȶ)
 
 
(ȡ)
ʈ 𐞯
107AF
ɖ 𐞋
1078B
c 
1D9C
ɟ 
1DA1
k 
1D4F
ɡ /g 
1DA2/1D4D
q 𐞥
107A5
ɢ 𐞒
10792
ʡ 𐞳
107B3
ʔ ˀ
02C0
Affricateʦ 𐞬
107AC
ʣ 𐞇
10787
ʧ 𐞮
107AE
(ʨ𐞫)
107AB
ʤ 𐞊
1078A
(ʥ𐞉)
10789
 𐞭
107AD
(𝼜)
 𐞈
10788
(𝼙)
Fricativeɸ 
1DB2
β 
1D5D
f 
1DA0
v 
1D5B
θ ᶿ
1DBF
ð 
1D9E
s ˢ
02E2
()
z 
1DBB
()
ʃ 
1DB4
(ɕ )
1D9D
ʒ 
1DBE
(ʑ )
1DBD
ʂ 
1DB3
()
ʐ 
1DBC
()
ç ᶜ̧
1D9C + 0327 [h]
ʝ 
1DA8
x ˣ
02E3
(ɧ 𐞗)
10797
ɣ ˠ
02E0
χ 
1D61
ʁ ʶ
02B6
ħ 𐞕
10795
(ʩ 𐞐)
10790
ʕ ˤ
02E4 [i]
h ʰ
02B0
()
ɦ ʱ
02B1
Approximantʋ 
1DB9
ɹ ʴ
02B4
ɻ ʵ
02B5
j ʲ
02B2
(ɥ )
1DA3
 
 
(ʍ )
AB69
ɰ 
1DAD
(w ʷ)
02B7
Tap/flap 𐞰
107B0
ɾ 𐞩
107A9
ɽ 𐞨
107A8
Trillʙ 𐞄
10784
r ʳ
02B3
ʀ 𐞪
107AA
ʜ 𐞖
10796
ʢ 𐞴
107B4
Lateral fricativeɬ 𐞛
1079B
(ʪ 𐞙)
10799
ɮ 𐞞
1079E
(ʫ 𐞚)
1079A
 𐞝
1079D
𝼅 𐞟
1079F
𝼆 𐞡
107A1
𝼄 𐞜
1079C
Lateral approximantl ˡ
02E1
( )
1DAA
 
 
(ȴ)
ɭ 
1DA9
ʎ 𐞠
107A0
ʟ 
1DAB
(ɫ ) [j]
AB5E
Lateral tap/flapɺ 𐞦
107A6
𝼈 𐞧
107A7
Implosiveƥɓ 𐞅
10785
ƭɗ 𐞌
1078C
𝼉 𐞍
1078D
ƈʄ 𐞘
10798
ƙɠ 𐞓
10793
ʠʛ 𐞔
10794
Click releaseʘ 𐞵
107B5
ǀ 𐞶
107B6
ʇǃ 
A71D
ʗ𝼊 𐞹
107B9
ψǂ 𐞸
107B8
𝼋(ʞ)
Lateral click
release
ǁ 𐞷
107B7
ʖ
Percussive¡ 
A71E [k]

The spacing diacritic for ejective consonants, U+2BC, works with superscript letters despite not being superscript itself: ᵖʼᵗʼᶜʼᵏˣʼ. If a distinction needs to be made, the combining apostrophe U+315 may be used: ̕̕̕ᵏˣ̕. The spacing diacritic should be used for a baseline letter with a superscript release, such as [tˢʼ] or [kˣʼ], where the scope of the apostrophe includes the non-superscript letter, but the combining apostrophe U+315 might be used to indicate a weakly articulated ejective consonant like [ᵗ̕] or [ᵏ̕], where the whole consonant is written as a superscript, or together with U+2BC when separate apostrophes have scope over the base and modifier letters, as in pʼᵏˣ̕. [12]

Spacing diacritics, as in , cannot be secondarily superscripted in plain text: ᵗʲ. (In this instance, the old IPA letter for [tʲ], ƫ, has a superscript variant in Unicode, U+1DB5 , but that is not generally the case.)

Among older letters, (U+A727) was a graphic variant of ɮ. Its superscript is supported at (U+AB5C). The most common letters with palatal hook are also supported; they are displayed in the table above. IPA once had an idiosyncratic curl on some of the palatalized letters: these are the fricative letters ʆʓ. Their superscript forms have been accepted for a future version of the Unicode Standard. [11] [9] The retired letters ƞ and ɼ have also been accepted for a future version of the Unicode Standard. [11] [9]

Among para-IPA letters, superscript Sinological ȡȴȵȶ have been accepted for a future version of the Unicode Standard. [10] [9] Superscripts of the Bantuist labio-dental plosives ȹ and ȸ have been accepted for a future version of the Unicode Standard. [10] [9] The central semivowels ɉ, ɥ̶, and have also been accepted for a future version of the Unicode Standard. [10] [9] [13]

Old-style click letters have been accepted for a future version of the Unicode Standard. [14] [9]

Vowel letters

The Unicode characters for superscript (modifier) IPA vowel letters, plus a pair of extended letters ᵿ found in English dictionaries, are as follows. Recently retired alternative letters such as ɩɷ are also supported; they are set off in parentheses and placed below the standard IPA letters:

IPA vowels and superscript variants
FrontCentralBack
Closei 
2071
y ʸ
02B8
ɨ 
1DA4
ʉ 
1DB6
ɯ 
1D5A
u 
1D58
Near-closeɪ 
1DA6
(ɩ )
1DA5
ʏ 𐞲
107B2




( )
1DA7


(ᵿ)



(ω)

ʊ 
1DB7
(ɷ 𐞤)
107A4
Close-mide 
1D49
ø 𐞢
107A2
ɘ 𐞎
1078E
ɵ 
1DB1
ɤ 𐞑
10791
o 
1D52
Midə 
1D4A
Open-midɛ 
1D4B
œ 
A7F9
ɜ 
1D9F
( )
1D4C
ɞ 𐞏
1078F
ʌ 
1DBA
ɔ 
1D53
Near-openæ 𐞃
10783
ɶ 𐞣
107A3
ɐ 
1D44
ɑ 
1D45
ɒ 
1D9B
Opena 
1D43

The precomposed Unicode rhotic vowel letters ɚɝ are not directly supported. The rhotic diacritic U+02DE ◌˞ should be used instead: ᵊ˞ ᶟ˞. [15]

ɜ and are reversed ɛ. The older IPA turned ɛ, , is also supported, at U+1D4C . However, the briefly resurrected vowel letter ʚ (U+029A) is not supported, only its reversed replacement ɞ is.

Among older letters, (U+1D1C), a graphic variant of ʊ, is supported at (U+1DB8). [16]

Among para-IPA letters, Sinological superscript ɿʅʮʯ have been accepted for a future version of the Unicode Standard. [10] [9] [13]

Length marks

The two length marks are also supported:

Length marks
LongHalf-long
ː 𐞁
10781
ˑ 𐞂
10782

These are used to add length to another superscript, such as Cʰ𐞁 or Cʰ𐞂 for long aspiration.

Wildcards

Superscript wildcards (full caps) are largely supported: e.g. ᴺC (prenasalized consonant), ꟲN (prestopped nasal), Pꟳ (fricative release), NᴾF (epenthetic plosive), CVNᵀ (tone-bearing syllable), Cᴸ (liquid or lateral release), Cᴿ (rhotic or resonant release), Vᴳ (off-glide/diphthong), Cⱽ (fleeting vowel). Superscript S for sibilant release has been accepted for a future version of the Unicode Standard; [13] [9] superscript for fleeting/epenthetic click has not. Other basic Latin superscript wildcards for tone and weak indeterminate sounds, as described in the article on the International Phonetic Alphabet, are mostly supported. (See table in previous section.)

Combining marks and subscripts

In addition, a very few IPA letters beyond the basic Latin alphabet have combining forms or are supported as subscripts:

Additional IPA characters
äɑæβçðəʃʍχʔʼ
Overscript◌ᷲ◌ᷧ◌ᷔ◌ᷩ◌ᷗ◌ᷙ◌ᷪ◌ᷯ◌̉ [l] ◌̓
Subscript
Underscript◌ᫀ◌̦

Composite characters

Primarily for compatibility with earlier character sets, Unicode contains a number of characters that compose super- and subscripts with other symbols. [1] In most fonts these render much better than attempts to construct these symbols from the above characters or by using markup.

Notes

  1. For a general overview and technical information on glyph substitution (though not specifically for fractions), see GSUB — Glyph Substitution Table in the OpenType specification on the Microsoft Typography site.
  2. Such as Andika, Arno Pro, Brill, Brioso Pro, Calibri, Candara, Carlito, Cantarell, FiraGO, EB Garamond, Gentium Book, Lato, Linux Libertine, Noto Sans, Noto Serif, Open Sans and Yrsa
  3. Such as Chrome, Firefox and Falkon
  4. Such as LibreOffice Writer
  5. Such as Adobe InDesign and Scribus
  6. ͺ is set lower than a normal subscript. It is equivalent to underscript ◌ͅ on a space.
  7. ◌̫ is traditionally typeset as an omega.
  8. Superscript ç is composed of superscript c and a combining cedilla, which should display properly in a good font. Superscript c was specifically requested for this purpose in Unicode proposal L2/03-180.
  9. U+02E4ˤMODIFIER LETTER SMALL REVERSED GLOTTAL STOP is the superscript variant of U+0295ʕLATIN LETTER PHARYNGEAL VOICED FRICATIVE and is defined for IPA use. The similar character U+02C1ˁMODIFIER LETTER REVERSED GLOTTAL STOP is a reversed U+02C0ˀMODIFIER LETTER GLOTTAL STOP, perhaps a gelded reversed question mark. Fonts are inconsistent in whether they look different and what the difference is.
  10. In Microsoft fonts, superscript ɫ was erroneously designed as a superscript .
  11. U+A71D and A71E were adopted as the Africanist equivalents of the IPA characters downstep and upstep. The correspondence of U+A71D to the IPA click letter ǃ is thus accidental. Coincidentally, U+A71E serves as the superscript variant of the extIPA percussive consonant ¡; the other percussive letters, ʬ and ʭ, do not have superscript support in Unicode.
  12. This is actually the Vietnamese diacritic dấu hỏi , not specifically IPA, but graphically both are gelded question marks.

References

  1. 1 2 3 "UCD: UnicodeData.txt". The Unicode Standard. Retrieved May 14, 2016.
  2. 1 2 Martin Dürst, Asmus Freytag (May 16, 2007). "Unicode in XML and other Markup Languages". W3C. Retrieved September 13, 2010.
  3. "fraction | Dart Package". Dart packages. December 27, 2021. Retrieved September 21, 2022.
  4. "MathML | General layout elements | Fractions". data2type GmbH (in German). March 30, 2021. Archived from the original on January 28, 2021. Retrieved January 13, 2022.
  5. Martin Dürst, Asmus Freytag (May 16, 2007). "Fraction Slash". W3C. Retrieved September 13, 2010.
  6. "UCD: Scripts.txt". The Unicode Standard. Retrieved September 21, 2022.
  7. Everson, Michael; West, Andrew (October 5, 2020). "L2/20-268: Revised proposal to add ten characters for Middle English to the UCS" (PDF).
  8. Kirk Miller (January 30, 2024). "L2/24-081: Unicode request for modifier capital S" (PDF).
  9. 1 2 3 4 5 6 7 8 9 10 11 "Proposed New Characters: Pipeline Table". Unicode Consortium. September 10, 2024. Retrieved September 21, 2024.
  10. 1 2 3 4 5 6 Kirk Miller (June 14, 2024). "L2/24-147: Modifier Sinological extensions to the IPA" (PDF).
  11. 1 2 3 4 Kirk Miller (June 6, 2024). "L2/24-171: Miscellaneous historical and para-IPA modifier letters" (PDF).
  12. Kirk Miller & Michael Ashby, L2/20-253R Unicode request for IPA modifier letters (b), non-pulmonic.
  13. 1 2 3 Kirk Miller (January 30, 2024). "L2/24-081: Latin Phonetic Trill and Small Capital" (PDF).
  14. Kirk Miller (April 26, 2024). "L2/24-052R: Unicode request for modifier pre-Kiel click letters" (PDF).
  15. Kirk Miller & Michael Ashby, L2/20-252R Unicode request for IPA modifier-letters (a), pulmonic
  16. Kirk Miller (January 30, 2024). "L2/24-081: Latin Phonetic The for Middle Tilde" (PDF).
  17. Silva, Eduardo Marín (March 1, 2017). "L2/17-066R: Proposal to encode the Marca Registrada sign" (PDF).